Nonmetallic electrode for spark plugs



Jan. 5 19'26Q H.RABEZZANA NONMETALLIC ELECTRODE FOR SPARK PLUGS Filed July 6, 1920 Patented Jan. 5, 1926.

UNITED STATES HECTOR BABEZZANA, OIE FLINT, MICHIGAN, ASSIGNOB TO A C SPARK PLUG- COMPANY PATENT OFFICE.

OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

NONMETALLIC ELECTRODE FOR SPARK PLUGS Application filed July 6, 1920. Serial No. 394,304.

To all whom it may concern Be it known that I, HECTOR RABnzzANA,

a subject of the King of Italy, and a resident of Flint, county of Genesee, and State of Michigan, have invented certain new and useful Improvements in Nonmetallic Electrodes for Spark Plugs, of which the follow ing is a full, clear, concise, and exact description, such as will enable others skilled in the art to which the invention relates to make and use the same, reference "being made therein to the accompanying drawings, which form a part of this specification.

My invention relates to spark plugs designed for use with internal combustion engines, and particularly to an inner electrode for a spark plug which electrode is carried by the insulating member of the plug and is located within a passage extending longitudinally thereof; and is made from a non-metallic material.

A further object of my invention is to provide an improved spark plug wherein the insulating member thereof is provided with a longitudinally extending passage along which the inner electrode extends, and which electrode is made from a basic granular electrical conducting material mixed with a suitable cementitious mate-rial to provide a plastic mass from which the electrode is formed.

A further object of my invention is to provide an improved spark plug wherein the inner electrode is made from a non-metallic plastic substance which 'is molded in place in a passage extending longitudinally of the insulator of the plug, so that the inner electrode and the insulating member form a single unitary structure when the plug is assembled and in use.

Further objects of my invention will appear from the following description and from the concluding claims it being appreciated, however, that my invention may be variously modified; and that the same includes all such variations and modifications of the particular embodiment thereof illustrated and described as come within the scope of the concluding claims.

In the drawing wherein the preferred embodiment of my invention is illustrated;

Figure 1 is a -v1ew showing my improved spark plug in section u on a plane located centrally and extending longitudinally thereof. I

Figure 2 is a view showing a modified form of my invention as regards the inner end of the central electrode thereof.

Figure 3 is a fragmentary view illustrating a form of terminal connector or cap difl'ering somewhat from the form shown in Figure 1.

Figure l is a similar fragmentary sectional view showing still another form of terminal connector or cap by which the leading-in conductor is attached to the plug.

Referring to the drawing, the reference numeral 5 designates the external metallic shell or casing of my improved spark plug, the same having a threaded inner end 6 whereby the same may be screwed into an opening provided for it in an internal combustion engine cylinder; and the reference numeral 7 designates the insulating member of the plug which is commonly made from porcelain or similar vitreous material.

This insulating member 7 is provided with a lower supporting shoulder 8 which lies above a ledge 9 provided within the casing of the plug and which ledge serves to support the insulating member, a suitable yieldable gasket 10 belng ordinarily interposed between the shoulder and the ledge to provide a better gas-tight joint or seal as is usual in spark lugs. The insulating memher is also provided with an upper shoulder 11 over which an annular ridge of the shell member 5 is forced during the manufacture of the plug to thereby provide an inturned ledge 12 whereby the insulator is held in place, in accordance with the usual practice in single piece spark plugs, a suitable yieldable gasket 13 being interposed between the shoulder 11 and the ledge in question to thereby prevent the breaking of the porcelain as the ledge 12 is forced inward and into holdin engagement. therewith.

The insu atin member 7 is provided with a' longitu inally extending passage and the referencenumeral 14 desi ates the inner electrode of the plug which inner electrode is made from a non-metallic material which, however, is a good conductor of electricity in order that the current may be made to pass through said electrode and across the spark gap 15 to the outer or shell electrode 16 of the plug, thereby producing sparks at the spark gap as is usual in spark plugs.

T e central electrode 14 may be made from various non-metallic and similar materials so long as the same is a sufliciently good conductor of electricity, among which materials may be mentioned graphite, carbon, and similar granular or finely divided conducting materials; the said basic material being bound together by a suitable cementi'tious material in order to provide a hard and resistant electrode and one which will maintain its integrity while in use; the cementitious and granular conducting material forming a plastic mass from which the electrodes are formed. The cementitious binding material may likewise be any material suitable for binding the particles from which the electrode is made together to thereby provide an electrode which will maintain its form while in use, among which materials may be mentioned sodium silicate and similar binding materials.

vThe non-metallicelectrode is molded in place within the passage provided for it in the insulating member from which it follows that the electrode is firmly anchored in place and an intimate contact is secured throughout the surface of the electrode and the passage along which it extends, which character of contact results in a better con-,

duction of heat along the electrode and to the insulator and a more effective dissipation of heat when the plug is in use.

The inner end of the central electrode adjacent the spark gap of the plug may be flush or substantially flush with the inner end of the insulating member as in the form of my invention illustrated in Figure 1, which is a form or construction in which the extremity of the electrode will be protected from disintegration to a marked degree by the insulating member whereby it is carried; or the inner end of said electrode may project somewhat beyond the inner end of the insulating member as shown at 17 in Figure 2 in which last mentioned case the relationship of the extremity of the grounded or shell electrode 18 may be varied relative to said inner end so long as the relation between the parts is such that sparks may pass between the electrodes when the plug is in use.

The electrical connection between the outer end of the inner electrode 14 and the cap or terminal of the plug to which the leadingin conductor is connectedmay be made in various ways. In the form of my invention illustrated in Figure 1 the outer end of the passage in the insulating member is threaded, and a threaded metallic rod 19 is cemented in place within said threaded portion with its inner end in contact with the central electrode at the point 20; said threaded rod having a nut 21 for the connection of a leadingin conductor to the said rod and electrode allid through which current is supplied to the p In the form of my invention shown in Figure 3 a metallic cap 22 is cemented to the outer end of the insulating member 23 by means of a layer of any suitable cement 24, and the upper end of the non-metallic electrode 25 extends to the end of the insulating member and is in contact with the interior surface of the cap to which the leading-in conductor is connected, as will be appreciated; while Figure 4 illustrates a form of my invention in which a metallic cap member 26 is provided with a depending portion which is forced inward as at 27 and into holding engagement with the outer end of the insulating member 28 to thereby hold the cap in place; a threaded connector 29 being held in place by the said cap and which connector has a depending pin portion 30 the end of which is in electrical contact with the central electrode 31, and a nut 32 for facilitating the connection of the leading in conductor with the inner electrode. As above stated, however, the manner in which a connection is provided between the leading-in conductor and the central electrode is quite immaterial; the essential features of my invention being an inner electrode made from a non-metallic conducting material molded in place within a passage extending longitudinally of the insulating member of the plug.

In View of,the premises it will be appreciated that I have dispensed with the usual inner metallic electrode commonly used in spark plugs which electrodes are ordinarily made from a metal or alloy which is quite expensive, thereby materially increasing the cost of the plug; and have substituted for said metallic electrode a non-metallic electrode which is much cheaper to produce, and which being molded in place within a passage provided for its reception in the insulating member provides a single unitary combined insulating member and inner electrode. Y

Furthermore, a molded inner electrode of the construction herein referred to may be made of large cross-sectional area, thereby reducing the electrical resistance of the plug; and the increased cross-sectional area of the inner electrode provides a plug in which the heat generated at the spark gap is conducted away therefrom and along the electrode more eflectively, because of the greater cross-sectional area of the electrode, than is the case in plugs in which a metallic electrode is employed the cross-sectional area of which is ordinarily reduced to a minimum consistent with the operation of the plug, because of the high cost of the materials-or alloys ordinarily deemed necessary for use in forming metallic inner electrodes. At the same time it has been found in practice that a molded electrode as herein disclosed possesses long life, as the same is subjected to little wear and disintegration by the passage of the sparks at the spark gap when the lug is in use.

It will as a matter 0 course be appreciated that the cross-sectionalform of the inner electrode is quite immaterial and may be varied as desired; and it will be further appreciated that the passage provided in the insulating member for the reception of the said electrode need not be carefully formed, slight irregularities as regards the passage being in fact desirable to a degree as they provide for a more secure anchoring of the electrode within the passage along which it extends. I

Having thus described and explained my invention, I claim and desire to secure by Letters Patent:

1.'In a spark plug of the class described,-

an insulating member having a longitudinally extending passage; an inner electrode formed from non-metallic plastic material molded in. place within and extending along said passage and the inner end of which is disposed in sparking relation to the external or grounded electrode of the plug; and means whereby a leading-in conductor may be electrically connected with said inner electrode and through which conductor a current of electricity may be supplied to the plug.

2. In a spark plug of the class described, an insulating member provided with a longitudinally extending passage; an inner electrode formed from agranular conducting material and a suitable binder molded in place within said passage, and the inner manent and end of which is arranged in sparking relation with the grounded or shell electrode of the plug, and is substantially flush with the inner end of the insulating member; and means for connecting a leading-in conductor with said inner electrode.

3. In a spark plug of the class described, an insulating member having a longitudinally extending passage; an inner electrode formed from non-metallic plastic material molded in place within said passage and the inner end of which'is disposed in sparking relation with the external or grounded electrode of the plug, and is substantially flush with the inner end of the insulating member; and a terminal with which the outer end of said inner electrode is in electrical contact and whereby a leading-in conductor may be electrically connected therewith.

4. In a spark plug of the class described, an insulating member having a longitudinally extending passage; and an inner electrode formed from a non-metallic material extending along said passage and molded in place therein, so that the insulating member and the electrode form a single unitary structure the arts of which are held in r- Exed relation to one anot er, the inner end of said inner electrode being disposed in sparking relation to the grounded electrodeof the plug, and said inner end being substantially flush with the inner end of the insulating member.

In testimony whereof I aflix my signature.

HECTOR RABEZZANA. 

